The present invention pertains to a new type of filter designed for the simultaneous preheating and filtration of the fuel injected in an internal combustion engine.
The invention applies more specifically to Diesel engines which consume fuel oil. The fuel oil obtained with the present refining processes has a high paraffin content. The congelation of the fuel oil occurs between 0.degree. C. and -2.degree. C., depending on the source of the fuel oil.
Since the congelation point of the fuel oil is close to 0.degree. C., a very common temperature during the winter season, it is the frequent cause of difficult starts of Diesel engines and the problems encountered with the fuel system during the operation of trucks and public work equipment.
It should be noted that these problems become pronounced after the prolonged storage of a Diesel engine vehicle at low ambient temperature. Under these conditions, the fuel oil system contains a significant amount of paraffin flakes or crystals which have a tendency to cake when the flow is interrupted by a barrier that they cannot clear. The filter and prefilter of the fuel oil constitute two barriers which, due to their functions, prevent the free flow of fuel oil as soon as the flakes have caked in front of the filtering element. As a result, the load drops significantly and does not allow the minimum flow of fuel required to feed the injection pump.